1. Technical Field
Aspects of this document relate generally to telecommunication systems and methods for signal interference cancellation for data transmission through a telecommunication channel.
2. Background Art
Conventional telecommunications systems utilize circuitry relating to interference cancellation such as that described in U.S. Publication No. 2002/0197958A1 (www.ptodirect.com/publication/?20020197958) which is herein incorporated by reference in its entirety. Conventional circuits have the following disadvantages:                a) The adaptive filter or least mean square (LMS) equalizer operates far from full scale which results in reduced precision and accuracy in cancellation performance. While the conventional circuit does have a front-end automatic gain control (AGC), this AGC optimizes only the analog-to-digital (A/D) dynamic range which is commonly implemented in digital communications systems.        b) The adaptive filter is only capable of correcting a limited range of phase errors just as the digital phase locked loop (DPLL) is which therefore results in the adaptive FIR filter and the DPLL having an increased chance of phase correction conflict.        c) When the adaptive filter has more taps (i.e. more than 11 taps), the phase tracking capability of the DPLL is slow, making adaptation more difficult.        d) The delay tracking capability is poor because when there is a delay handover from the adaptive equalizer to the delay manager, there is no practical way for the DPLL to adjust to the change immediately. This leads to difficulty in tracking a high Doppler rate of change.        e) The adaptive FIR filter has to be complex because phase and frequency correction of the interference is done before the adaptive FIR filter. In applications where spectrum linear distortion is minimal, the complex adaptive FIR filter requires unnecessary extra resources.        
U.S. Pat. No. 4,736,455, which is herein incorporated by reference in its entirety, includes another example of a conventional interference cancellation system. Like the above described conventional interference cancellation system, implementations of the present interference cancellation system may be used in multiple carrier frequency reuse communications systems, such as satellite communications systems.